The SCE or DC was defined in 3GPP (3rd Generation Partnership Project) RAN (Radio Access Network) working groups, and it has initiated a study on security aspect and impact on the architecture 1A defined in NPL 1.
For user plane data transmission between UE and SeNB, a new key for the confidentiality protection is needed. The RRC (Radio Resource Control) signaling terminates in the MeNB (Master eNB), thus it is responsible for the key management.
In current architecture disclosed in NPL 1, each UE is connected to one MeNB and one SeNB. There can be multiple bearers between SeNB and UE. The key for UE and SeNB user plane communication protection, denoted as S-KUPenc, is derived at SeNB and UE from a key S-KeNB shared between UE and SeNB. The S-KeNB is derived at MeNB and sent to SeNB. UE derives the same S-KeNB at its side.